Billet heating coil

ABSTRACT

An induction heating coil arrangement is disclosed which includes coil means having a longitudinal axis and defined by a pair of coil portions which are supported in suspension by means providing for pivotal movement of the portions toward and away from one another in a direction lateral to the axis of the coil means. Lateral separation of the coil portions facilitates the longitudinal introduction therebetween of a metal workpiece to be heated. Support means is provided for a workpiece to be heated, and when the coil sections are laterally closed relative to one another they are disposed in inductive heating relationship with respect to a workpiece on the support means. Means are provided to vertically displace a section of each coil portion relative to the remainder thereof both to facilitate movement of the coil portions into inductive heating relationship with a workpiece and to provide for the coil means to be adjustable to receive workpieces of various thicknesses.

United States Patent 1 Kasper 5] May 1, 1973 1 1 BILLET HEATING COIL Primary Examiner-C. L. Albritton Assistant Examiner-13. A. Reynolds [75] Inventor. Rottiliigrt Jerry Kasper, Seven Hills, An0mey MeyerTilbeny and Body [73] Assignee: Park-Ohio Industries, Inc., Cleve- BSTRACT landohlo An induction heating coil arrangement is disclosed [22] Fil d; S t, 24, 1971 which includes coil means having a longitudinal axis Appl. No.: 183,467

and defined by a pair of coil portions which are supported in suspension by means providing for pivotal movement of the portions toward and away from one another in a direction lateral to the axis of the coil means. Lateral separation of the coil portions facilitates the longitudinal introduction therebetween of a metal workpiece to be heated. Support means is provided for a workpiece to be heated, and when the coil sections are laterally closed relative to one another they are disposed in inductive heating relationship with respect to a workpiece on the support means. Means are provided to-vertically displace a section of each coil portion relative to the remainder thereof both to facilitate movement of the coil portions into inductive heating relationship with a workpiece and to provide for the coil means to be adjustable to receive workpieces of various thicknesses.

18 Claims, 5 Drawing Figures Patented May 1, 1973 3,731,040

3 Sheets-Sheet 1 INVENTOR. ROBERT J. CASPER BY Mew, 7dmaq 8 Bad;

ATTORNEYS Patented May 1, 1973 3,731,040

3 Sheets-Sheet 2 FIGS I IN VENTOR. I ROBERT J. CASPER BY Mega, 7M 8 Bad;

ATTORN EYS Patented May 1, 1973 3,731,040

5 Sheets-Sheet 5 INVEN'TOR. ROBERT J. CASPER BY Me 7414mm; 3

ATTORNEYS BILLET HEATING COIL This invention relates to the art of induction heating and, more particularly, to induction heating coil arrangements.

Induction heating coils have been provided heretofore for the purpose of inductively heating a metal workpiece or ingot. Most often, the coils of such units are defined by a continuous tube of conductive, nonmagnetic material such as copper through which cooling fluid is circulated and the opposite ends of which are connected across a suitable source of alternating current. The conductors of such coil units may have a circular configuration or a rectangular configuration when viewed in the direction of the axis thereof depending on the configuration of the workpiece or ingot to be heated. Moreover, such coils are embedded in walls of a refractory insulating material which define a chamber within a coil generally conforming in contour and cross-sectional dimensions to the contour and cross-sectional dimensions of the workpiece to be heated.

Coil units of the above character are usually disposed with the axes thereof extending horizontally or vertically. Horizontal disposition of the coil means is often desired and is of particular advantage in that it permits the selective use of an open ended coil to achieve either static or continuous progressive heating of a workpiece. Regardless of whether such a horizontally disposed coil is employed to progressively heat an elongated billet or workpiece or to statically heat a workpiece, there are problems attendant to the use of the coils. in this respect, means must be provided to support the workpiece for introduction into the coil and to support the workpiece during heating thereof. If the workpiece is longer than the coil, such as where the workpiece is to be progressively heated, means must be provided adjacent opposite ends of the coil to support the workpiece for movement relative to the coil. While the requirements for adequately supporting the workpiece may not be too difficult to overcome problems are encountered in the movement of a workpiece, or a longitudinal section thereof, relative to the coil means and in establishing the most desirable positional relationship therebetween, vertically and laterally, for the induction heating process. In this respect, the workpiece must be properly positioned horizontally and vertically relative to the coil means prior to relative movement therebetween, and such alignment must be maintained during the relative movement. The failure to properly align the workpiece and coil means and maintain such alignment may result in undesirable engagement of the workpiece with the coil means and possible damage to the coil means and/or the workpiece. Moreover, misalignment during the induction heating process adversely affects uniform heating penetration of the workpiece. Heretofore, such alignment and maintenance of alignment could not be achieved readily and economically. In this respect, for example, manual alignment is time consuming and too inaccurate, and the use of mechanical aligning devices involves considerable expense both with regard to initial cost and with regard to repair, replacement or maintenance costs. Moreover, most mechanical devices required frequent adjustment, whereby production time is lost.

Another disadvantage of horizontal coil arrangements heretofore known lies in the fact that the coil assembly is mounted in a stationary disposition relative to underlying support surface means, and the inner cross- 5 sectional dimensions of the chamber extending axially therethrough are fixed, whereby use of the coil mechanism is limited to the heating of billets or workpieces having cross-sectional dimensions within those of the coil. Moreover, when the cross-sectional dimensions of the workpiece and coil means are such that a minimum of clearance exists therebetween, the necessity for alignment is more critical in order to prevent damage to the coil means and/or workpiece during relative-movement therebetween.

The foregoing disadvantages, and others, relating to the structure and use of horizontal coil arrangements heretofore known are advantageously avoided in accordance with the present invention. In this respect, suspended coil means is provided which has a horizonas a unit from a use position relative to a work station to a non-use position in which it is disposed above the work station. It will be appreciated that such an arrangement advantageously provides, if desired, for a plurality of coil units to be supported above a work station for use therewith, selectively, to desirably provide versatility to a work line by providing, for example, for the line to handle a variety of workpiece or for the line to be maintained in use while a given coil unit associated therewith is being replaced, repaired or the like. Moreover, a coil unit is provided in accordance with the present invention which includes means advantageously providing for readily aligning a workpiece relative thereto when the coil means is moved into its use position. Accordingly, a workpiece to be heated need only be positioned on the support means therefor in an approximately aligned position relative to the axis of the coil unit, whereby a considerable savings in time and expense is realized relative to the use of special aligning devices or manual alignment. Still further, the. coil means is of a construction which permits adjustment thereof to be achieved so that, for a given coil unit, workpieces having various cross-sectional dimensions can be inductively heated by the coil means. Accordingly, only one coil unit made in accordance with the present invention is necessary where heretofore a plurality of coil units would have to be employed to achieve heating of such workpieces.

F An outstanding object of the present invention is the provision of induction heating apparatus including suspended coil means which is disposed with its axis horizontal and is movable into and out of induction heating relationship with a workpiece supported therebeneath.

Another object of the present invention is the provitally extending axis and which is adapted to be moved respectively,

Still another object of the present invention is the provision of induction heating apparatus of the above character in which portions of the coil unit are adjustable relative to one another in a given direction to provide for workpieces having various dimensions in the given direction to be inductively heated by the coil unit. 7

The foregoing objects, and others, will in part be obvious and in part more fully pointed out hereinafter in conjunction with the description of the drawing of preferred embodiments of the present invention and in which:

FIG. 1 is a perspective, schematic illustration of induction heating coil means made in accordance with the present invention;

FIG. 2 is a side elevation of induction heating apparatus made in accordance with the present invention employing the coil unit illustrated in FIG. 1;

FIG. 3 is a sectional elevation view of the apparatus illustrated in FIG. 2, the section being taken along line 33 in FIG. 2;

FIG. 4 is an end elevation of the apparatus as viewed along line 4--4 in FIG. 2; and

FIG. 5 is a plan view of the apparatus illustrated in FIG. 2.

Referring now to the drawing in greater detail wherein the showings are for the purpose of illustrating preferred embodiments of the present invention only and not for the purpose of limiting the same, an induction heating coil unit is schematically illustrated in FIG. I of the drawing and is defined by a pair of coil portions 12- and 14 which together define a continuous coil having opposite ends 16 and 18 connected across a suitable source of alternating current 20. Coil portion 12 includes upper and lower coil sections 20 and 22, i

and coil portion 14 is defined by upper and lower coil sections 24 and 26, respectively. Each of the coil sections 20, 22, 24 and 26 is comprised of a plurality of tubular conductors 28 of conductive material such as copper which extend generally parallel to axis A of the coil unit and have their opposite ends contoured in a manner whereby an axial opening is defined through the coil unit. Moreover, in a manner well known, the conductors of each coil section are embedded in corresponding suitable bodies of refractory insulating material, as illustrated by broken lines in FIG. 1. While the ends of conductors 28 in the embodiment illustrated are contoured to define a rectangular opening through the coil, it will be appreciated that the end portions can be contoured to provide any desired cross-sectional contour for the opening through the coil. Conductors 28 of coil sections 20 and 22 together define a continuous coil portion and, in this respect, the corresponding end of conductors 28 at opposite ends of coil portion 12 are interconnected by corresponding flexible lead means 30. Similarly, the corresponding ends of conductors 28 of coil sections 24 and 26 at opposite ends of coil portion 14 are interconnected by flexible lead means 32. As pointed out more fully hereinafter, coil sections 20 and 22 are vertically displaceable relative to one another and flexible lead means 30 permits such movement. Similarly, coil sections 24 and 26 are vertically displaceable relative to one another and flexible lead means 32 permits such movement therebetween. Coil portions 12 and 14 are electrically interconnected adjacent one end thereof by flexible lead means 34 interconnecting one of the conductors 28 of coil section 24 with one of the conductors 28 of coil section 20. Flexible lead means 34 permits coil portions 12 and 14 to be moved laterally relative to one another and to coil axis A. In a manner well known in the art, cooling fluid is circulated through the tubular conductors of coil means 10 and for this purpose, ends 16a and 18a of the coil unit define inlet and outlet means, respectively, for cooling fluid. Further, to facilitate the circulation of cooling fluid through the coil unit flexible lead means 30, 32 and 34 may be tubular components of flexible, inductive material. Alternatively, the flexible lead may be in the form of flexible,

' stranded cables or the like electrically interconnecting conductors 28, in which case the opposed ends of the tubular conductors would be connected for flow communication therebetween by suitable flexible hose means or the like of non-conducting material.

Induction heating apparatus made in accordance with the present invention and employing a coil unit of the character described in conjunction with FIG. 1 is illustrated in FIGS. 2, 3, 4 and 5 of the drawing. The apparatus, designated generally by the numeral 40, is adapted to be supported in suspension for vertical reciprocating movement by support means including suitable overhead support means, not illustrated. The support means for the apparatus further includes a pair of arm elements 42 and 44 adjacent opposite ends of coil unit 10. The upper ends of arm elements 42 and 44 are overlapped and are pivotally interconnected with pin means 46 which extend through suitable openings in the arm elements. Arm elements 42 and 44 are adapted to be interconnected with the overhead support means in any suitable manner and, for example, pin means 46 may be provided with ends 48 projecting outwardly from the corresponding arm element 44 and interconnected with corresponding support arms 50 depending from the overhead support means. The lower ends of arm elements 42 and 44 terminate in inwardly extending end portions 43 and 45, respectively, and are interconnected with coil portions 12 and 14, respectively, of coil unit-10. Thus, the coil'portions are pivotally supported in suspension for lateral movement between first and second positions relative to one another. More particularly, coil portions 12 and 14 are supported for movement laterally away from one another from a first position indicated by the solid line dispositions thereof in FIG. 3 in which the coil portions are disposed in inductive heating relationship with respect to a workpiece W therebetween to a second position indicated by the broken line dispositions of the coil portions in FIG. 3 and in which the coil portions are laterally spaced from the corresponding side of workpiece W. When the coil portions are in the latter positions thereof, workpiece W is exposed.

Pivotal movement of arm elements 42 and 44 to move coil portions 12 and 14 between the first and second positions thereof is achieved by means such as hydraulic or pneumatic motor means 54 extending laterally between a pair of cylindrical rod components 51 and 53 which extend longitudinally between arm elements 42 and 44, respectively, and have their opposite ends suitably interconnected therewith such as by welding. More particularly, hydraulic or pneumatic motor means 54 includes cylinder means 56 and piston means including piston rod means 58 extending from one end of cylinder means 56. One end 60 of cylinder means 56 is pivotally interconnected with rod 51 and the opposite end of the motor means defined by the outer end 62 of piston rod means 58 is pivotally interconnected with rod 53. The specific structure of motor means 54 does not form a part of the present invention and, accordingly, will not be discussed indetail. It will be understood, however, that cylinder means 56 is adapted to be connected to a source of hydraulic fluid or air, not illustrated, the flow of which is controlled in a manner whereby piston rod means 58 reciprocates axially relative to cylinder means 56 to displace rods 51 and 53 relative to the axis of pin means 46, thus to cause pivotal displacement of arms 42 and 44 in laterally opposite directions about the axes of pin.

means 46. It will be appreciated, of course, that each pair of arms 42 and 44 could be provided with corresponding motor means disposed therebetween as opposed to the arrangement of common motor means herein illustrated.

With further regard to the relationship between arms 42 and 44 and coil portions 12 and 14, it will be seen that the upper and lower horizontal surfaces and the outer vertical surfaces of coil sections 20 and 22 of coil portion 12 are bounded by corresponding angular plate means 64 and 65, and that the corresponding surfaces of coil sections 24 and 26 of coil portion 14 are similarly bounded by angular plate means 66 and 67. Plate means 64, 65, 66 and 67 may be of any suitable non-magnetic metal, preferably are substantially longitudinally coextensive with the corresponding coil section, and are interconnected with the corresponding coil section in any suitable manner, Further, the vertically extending side portions 65a and 67a of plate means 65 and 67 of coil sections 22 and 26 extend upwardly into interengagement with inwardly extending end portions 43 and 45, respectively, of arms 42 and 44. interengagement between the side portions 65a and 67a of the coil sections and portions 43 and 45 of the arms may be achieved in any suitable manner such as by notch means in one or the other thereof, or cooperating notch means therebetween. Further, coil sections 22 and 26 are rigidly interconnected with the corresponding arm portions 43 and 45 such as by welding or bolting the vertically extending portions of plate means 65 and 67 thereto. A bolted interconnection may be preferred in that it provides for removing the coil sections from the arms for purpose of repair, maintenance or replacement.

The lower edges of the vertically extending portions 64a and 66a of plate means 64 and 66 overlie the upper surfaces of arm portions 43 and 45, respectively. Moreover, the outer surfaces 64b and 66b of the vertically extending portions of plate means 64 and 66 are provided with vertically extending slot means 68 and 70, respectively, adapted to receive correspondingly contoured projection means 72 and 74 extending vertically along the inner edges of arms 42 and 44, respectively. Preferably, slot means 68 and 70 and the corresponding projection means 72 and 74 are of dove-tail contour in cross-section to facilitate lateral retention and longitudinal positioning of the coil sections relative to the corresponding support arm. Further, the slot and projection means are cooperable to slidably support the corresponding coil section for vertical reciprocating movement relative to the corresponding support arm. Cross-sectional contours other than the dove tailed contour illustrated can, of course, be employed to achieve the support and guide functions. It will be appreciated .too that the slot and projection means could be cooperatively contoured simply to provide for guiding coil section movement, and means other than the slot and projection means could be employed to provide for lateral retention and longitudinal positioning of the coil sections relative to the corresponding support arms.

Vertical reciprocating movement of coil sections 20 and 24 is achieved by means of corresponding hydraulic or pneumatic motor means 76 and 78 disposed between the upper surface of the horizontally extending portions of plate means 64 and 66 and plate means 80 and 82 extending longitudinally between support arms 42 and 44, respectively. More particularly, plate means 80 extends between and is rigidly attached to support arms 42 at opposite ends of the coil unit, and bracket means 82 extends longitudinally between and is rigidly attached to support arms 44. Motor means 76 and 78 are disposed substantially midway between the support arms at opposite ends of the coil unit and have their upper ends suitably attached to the corresponding plate means 80 and 82 and their lower ends pivotally interconnected with the corresponding plate means 64 and 66 of coil sections 20 and 24. Motor means 76 and 78 are cylinder and piston type units operable when energized to impart vertical reciprocating movement to the corresponding coil section relative to the corresponding support arm. Actuation of the motor means is achieved by fluid or air under pressure delivered thereto from a suitable source of supply, not illustrated, and which delivery, of course, is controlled in a manner to achieve the desired operation thereof. Moreover, it will be appreciated that motor means 76 and 78 may be operated simultaneously or individually as desired to impart vertical movement to coil sections 20 and 24. Still further, it will be appreciated that a plurality of such motor units could be associated with each coil section and spaced apart along the length thereof.

In operation of the apparatus as thus far described, a workpiece W is supported during heating thereof by support means 84 at opposite ends of the apparatus. Support means 84 may be defined, for example, by horizontally disposed roller elements which advantageously support the workpiece for longitudinal movement relative to the coil unit. Presuming that the section of the workpiece within the coil unit has been heated, motor means 54 is actuated to cause pivotal displacement of support arms 42 and 44 about the axes of pin means .46 to move coil portions 12 and 14 laterally outwardly from the corresponding side of the workpiece. The entire apparatus may then be elevated to the extent desired and support means 52 which is disposed beneath the coil unit during the heating operation is elevated to engage the under surface of workpiece W to further facilitate support of the workpiece during longitudinal movement thereof. Workpiece W is then advanced longitudinally relative to the coil unit to bring another portion thereof into position for heating. Support means 52 is then lowered to the position thereof illustrated in FIGS. 2 and 3. Apparatus 40 is then lowered to the position thereof illustrated by broken lines in FIG. 3, and motor means 54 is actuated to close coil portions 12 and 14 to the full line positions thereof illustrated in FIG. 3, whereby coil portions 12 and 14 aredisposed in induction heating relationship with respect to workpiece W.

Proper relative alignment between the workpiece and coil means is necessary to reasons set forth hereinbefore, and such relative alignment is advantageously provided for in accordance with the present invention. In this respect, with reference to FIGS. 2 and 4 of the drawing, orienting means 86 is provided at opposite ends of the coil unit for initially orienting the coil unit vertically and laterally relative to workpiece W. More particularly, orienting means 86 includes lateral guide means 88 in the form of a pair of depending arms 90 laterally spaced apart a distance slightly greater than the width of workpiece W and having laterally outwardly flared lower ends 91. In the embodiment illustrated, arms 90 are supported in a fixed position relative to the axes of pin means 46 of the apparatus so as to be vertically movable with the apparatus. More particularly with regard to the disclosed embodiment, support means 50 includes a portion depending below pin means 46 and thence axially outwardly from the corresponding end of the coil unit. Arms 90 depend from opposite sides of plate portion 92, as illustrated in FIG. 4. It will be readily appreciated that the lateral guide means can be defined by a structure other than the specific structure thereof illustrated. Orienting means 86 further includes positioning means 94 for vertically positioning apparatus 40 relative to workpiece W. In the embodiment illustrated, positioning means 94 is defined by a roller element 96 depending from and suitably interconnected with plate portion 92 so as to engage the upper surface or workpiece W.

Orienting means 86 operates to initially assure proper alignment between the workpiece and coil portions 12 and 14 when apparatus 40 is lowered relative to the workpiece. In this respect, as apparatus 40 is lowered arms 90 of guide means 88 receive workpiece W therebetween and by having the lower ends 91 thereof flared outwardly as illustrated in FIG. 4, any initial misalignment between workpiece W and the coil means will be corrected by relative lateral displacement of the workpiece and coil unit upon engagement of the workpiece by one or the other of the arms of the guide means. Engagement of roller means 96 with the' upper surface of workpiece W indicates proper vertical orientation of the apparatus relative to the workpiece. Suitable means, not illustrated, can be provided to stop vertical descent of the apparatus upon engagement of roller 96 with the workpiece. At this point, the apparatus is positioned as is illustrated in FIG. 3 with coil units 12 and 14 spaced laterally outwardly from opposite sides of workpiece W. Motor means 54 is then actuated to pivot support arms 42 and 44 toward one another to bring coil portions 12 and 14 into closed relationship relative to workpiece W. The inner most ends 47 and 49 of portions 43 and 45 of support arms 42 and 44, respectively, define stop surfaces adapted to engage corresponding sides of workpiece W when coil portions 12 and 14 are in their fully closed positions. It will be appreciated, that stop surfaces 47 and 49 by engaging opposite sides of the workpiece also operate to assure proper final lateral alignment of workpiece W relative to coil portions 12 and 14. It will be appreciated that the provision of stop surfaces 47 and 49 also provides for coil portions 12 and 14 to be properly laterally oriented with respect to workpieces having various lateral widths.

Vertical movement of coil section 20 relative to coil section 22 by motor means 76 and movement of coil section 24 relative to coil section 26 by motor means 78 provides for coil portions 12 and 14 to be adjustable to facilitate the induction heating of workpieces of various thicknesses. Further, such vertical movement of coil sections 20 and 24 permits the space between the upper and lower coil section of coil portions 12 and 14 to be increased prior to lateral movement of the coil portions relative to the workpiece between the first and second positions thereof so as to assure that there will be no interference between the workpiece and coil portions such as by contact therebetween during such movement. Such alignment capabilities further assure avoiding engagement of the coil sections with the workpiece which might otherwise result in damage to the coil section or workpiece.

As many possible embodiments of the present invention may be made and as many possible changes may be made in the embodiment herein set forth, it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the present invention and not as a limitation.

I claim:

1. Apparatus for inductively heating a metal workpiece comprising, support means for a workpiece to be heated, heating coil means including relatively movable coil portions, means supporting said coil portions in suspension for movement in opposite directions between first and second positions relative to one another, said coil portions in one of said first and second positions each being disposed in inductive heating relationship with respect to a workpiece on said workpiece support means and in the other of said positions being laterally spaced from said work piece, means to move said coil portions relative to one another, and means connecting said coil means to a source of alternating current.

2. Apparatus according to claim 1, wherein said means supporting said coil portions in suspension includes means to support said coil portions for pivotal movement relative to one another.

3. Apparatus according to claim 1, wherein each of said coil portions has an axis and includes coil sections relatively movable in a direction substantially transverse to the axis of the coil portion, and means to move said coil sections of each coil portion relative to one another.

4. Apparatus according to claim 3, wherein said coil sections of each coil portion include an upper coil section and a lower coil section, said means to move said coil sections including means to move said upper section of each coil portion relative to the corresponding lower section.

5. Apparatus according to claim 1, wherein said means supporting said coil portions includes means to relatively position said coil portions and a workpiece on said workpiece support means.

6. Apparatus according to claim 1, wherein said means to move said coil portions is operable to move said coil portions in laterally opposite directions relative to one another and to corresponding sides of said workpiece support means.

7. Apparatus according to claim 6, wherein said means supporting said coil portions includes means to relatively position said coil portions and a workpiece on said workpiece support means.

8. Apparatus for inductively heating a metal workpiece comprising, support means for a workpiece to be heated, heating coil means including relatively movable coil portions, means supporting said coil portions in suspension for movement between first and second positions relative to one another, said coil portions in one of said first and second positions being disposed in inductive heating relationship with respect to a workpiece on said workpiece support means and in the other of said positions being laterally spaced apart relative to said workpiece, means to move said coil portions in laterally opposite directions relative to one another and to corresponding sides of said workpiece support means, means connecting said coil means to a source of alternating current, said coil portions each including coil sections relatively movable in a direction substantially transverse to the axis of the coil portion, and means to move said coil sections of each coil portion relative to one another.

9. Apparatus for inductively heating a metal workpiece comprising, support means for a workpiece to be heated, heating coil means including relatively movable coil portions, means supporting said coil portions in suspension for movement between first and second positions relative to one another, said coil portions in one of said first and second positions being disposed in inductive heating relationship with respect to a workpiece on said workpiece support means and in the other of said positions being laterally spaced apart relative to said workpiece, means to move said coil portions in laterally opposite directions relative to one another and to corresponding sides of said workpiece support means, and means connecting said coil means to a source of alternating current, said coil portion support means being vertically movable when said coil portions are in said other of said first and second positions to move said coil portions to a third position above said other position.

10. Apparatus for inductively heating a metal workpiece comprising, support means for a workpiece to be heated, heating coil means including relatively movable coil portions, means supportingsaid coil portions in suspension for movement between first and second positions relative to one another, said coil portions in one of said first and second positions being disposed in inductive heating relationship with respect to a workpiece on said workpiece support means and in the other of said positions being laterally spaced apart relative to said workpiece, meansto move said coil portions relative to one another, and means connecting said coil means to a source of alternating current, said means supporting said coil portions in suspension being vertically movable to move said coil portions vertically between said other of said first and second positions and a third position above said other position.

11. Apparatus for inductively hea mg a metal workpiece comprising support means for a workpiece to be heated, heating coil means including relatively movable coil portions, coil portion support means including arm means for each coil portion having opposite ends, one of said opposite ends of each arm means being interconnected with the corresponding coil portion and the other of said opposite ends being mounted for pivotal movement of said arm means about parallel axes spaced above said coil portions, whereby said coil portions are supported in suspension by said arm means for pivotal movement about said axes and between first and second positions, said coil portions in one of said first and second positions being disposed in inductive heating relationship with respect to a workpiece on said workpiece support means and in the other of said positions being laterally spaced apart and disposed outwardly of the corresponding side of said workpiece, means to move said coil portions between said first and second positions, and means connecting said coil means to a source of alternating current.

12. Apparatus according to claim 11, wherein said coil portions each include coil sections relatively movable in a direction substantially transverse to the axis of the coil portion, and means to move said coil sections of each coil portion relative to one another.

13. Apparatus according to claim 12, wherein said coil sections of each coil portion include upper and lower coil sections, said means to move said coil sections including means to move said upper section of each coil portion vertically relative to the corresponding lower section.

14. Apparatus according to claim 13 wherein said arm means are movable vertically, whereby when said coil portions are in said other of said first and second positions said coil portions can be moved vertically between said other position and a third position above said other position.

15. Apparatus according to claim 14, wherein said coil portion support means includes means to relatively position said coil portions and a workpiece on said workpiece support means.

16. Apparatus according to claim 15, wherein said positioning means includes means to position said coil portions laterally and vertically relative to said workpiece when said coil portions are moved from said third position to said other position, and means to laterally position said coil portions and said workpiece when said coil portions are moved from said other position to said one position.

17. Apparatus according to claim 11, wherein said arm means are movable vertically, whereby when said coil portions are in said other of said first and second positions said coil portions can be moved vertically between said other position and a third position above said other position.

18. Apparatus according to claim 11, wherein said coil portion support means includes means to relatively position said coil portions and a workpiece on said workpiece support means. 

1. Apparatus for inductively heating a metal workpiece comprising, support means for a workpiece to be heated, heating coil means including relatively movable coil portions, means supporting said coil portions in suspension for movement in opposite directions between first and second positions relative to one another, said coil portions in one of said first and second positions each being disposed in inductive heating relationship with respect to a workpiece on said workpiece support means and in the other of said positions being laterally spaced from said workpiece, means to move said coil portions relative to one another, and means connecting said coil means to a source of alternating current.
 2. Apparatus according to claim 1, wherein said means supporting said coil portions in suspension includes means to support said coil portions for pivotal movement relative to one another.
 3. Apparatus according to claim 1, wherein each of said coil portions has an axis and includes coil sections relatively movable in a direction substantially transverse to the axis of the coil portion, and means to move said coil sections of each coil portion relative to one another.
 4. Apparatus according to claim 3, wherein said coil sections of each coil portion include an upper coil section and a lower coil section, said means to move said coil sections including means to move said upper section of each coil portion relative to the corresponding lower section.
 5. Apparatus according to claim 1, wherein said means supporting said coil portions includes means to relatively position said coil portions and a workpiece on said workpiece support means.
 6. Apparatus according to claim 1, wherein said means to move said coil portions is operable to move said coil portions in laterally opposite directions relative to one another and to corresponding sides of said workpiece support means.
 7. Apparatus according to claim 6, wherein said means supporting said coil portions includes means to relatively position said coil portions and a workpiece on said workpiece support means.
 8. Apparatus for inductively heating a metal workpiece comprising, support means for a workpiece to be heated, heating coil means including relatively movable coil portions, means supporting said coil portions in suspension for movement between first and second positions relative to one another, said coil portions in one of said first and second positions being disposed in inductive heating relationship with respect to a workpiece on said workpiece support means and in the other of said positions being laterally spaced apart relative to said workpiece, means to move said coil portions in laterally opposite directions relative to one another and to corresponding sides of said workpiece support means, means connecting said coil means to a source of alternating current, said coil portions each including coil sections relatively movable in a direction substantially transverse to the axis of the coil portion, and means to move said coil sections of each coil portion relative to one another.
 9. Apparatus for inductively heating a metal workpiece comprising, support means for a workpiece to be heated, heating coil means including relatively movable coil portions, means supporting said coil portions in suspension for movement between first and second positions relative to one another, said coil portions in one of said first and second positions being disposed in inductive heating relationship with respect to a workpiece on said workpiece support means and in the other of said positions being laterally spaced apart relative to said workpiece, means to move said coil portions in laterally opposite directions relative to one another and to corresponding sides of said workpiece support means, and means connecting said coil means to a source of alternating current, said coil portion support means being vertically movable when said coil portions are in said other of said first and second positions to move said coil portions to a third position above said other position.
 10. Apparatus for inductively heating a metal workpiece comprising, support means for a workpiece to be heated, heating coil means including relatively movable coil portions, means supporting said coil portions in suspension for movement between first and second positions relative to one another, said coil portions in one of said first and second positions being disposed in inductive heating relationship with respect to a workpiece on said workpiece support means and in the other of said positions being laterally spaced apart relative to said workpiece, means to move said coil portions relative to one another, and means connecting said coil means to a source of alternating current, said means supporting said coil portions in suspension being vertically movable to move said coil portions vertically between said other of said first and second positions and a third position above said other position.
 11. Apparatus for inductively heating a metal workpiece comprising support means for a workpiece to be heated, heating coil means including relatively movable coil portions, coil Portion support means including arm means for each coil portion having opposite ends, one of said opposite ends of each arm means being interconnected with the corresponding coil portion and the other of said opposite ends being mounted for pivotal movement of said arm means about parallel axes spaced above said coil portions, whereby said coil portions are supported in suspension by said arm means for pivotal movement about said axes and between first and second positions, said coil portions in one of said first and second positions being disposed in inductive heating relationship with respect to a workpiece on said workpiece support means and in the other of said positions being laterally spaced apart and disposed outwardly of the corresponding side of said workpiece, means to move said coil portions between said first and second positions, and means connecting said coil means to a source of alternating current.
 12. Apparatus according to claim 11, wherein said coil portions each include coil sections relatively movable in a direction substantially transverse to the axis of the coil portion, and means to move said coil sections of each coil portion relative to one another.
 13. Apparatus according to claim 12, wherein said coil sections of each coil portion include upper and lower coil sections, said means to move said coil sections including means to move said upper section of each coil portion vertically relative to the corresponding lower section.
 14. Apparatus according to claim 13 wherein said arm means are movable vertically, whereby when said coil portions are in said other of said first and second positions said coil portions can be moved vertically between said other position and a third position above said other position.
 15. Apparatus according to claim 14, wherein said coil portion support means includes means to relatively position said coil portions and a workpiece on said workpiece support means.
 16. Apparatus according to claim 15, wherein said positioning means includes means to position said coil portions laterally and vertically relative to said workpiece when said coil portions are moved from said third position to said other position, and means to laterally position said coil portions and said workpiece when said coil portions are moved from said other position to said one position.
 17. Apparatus according to claim 11, wherein said arm means are movable vertically, whereby when said coil portions are in said other of said first and second positions said coil portions can be moved vertically between said other position and a third position above said other position.
 18. Apparatus according to claim 11, wherein said coil portion support means includes means to relatively position said coil portions and a workpiece on said workpiece support means. 